Neat trick: Remember when the best graphics cards only took up a single slot in your PC case? Those days are long gone, with even lower-end cards taking up considerable space in the back of your PC. But what if you could cut an RTX 4090's volumetric footprint by more than half? That's what Optimum Tech did with an aftermarket GPU water block.

Today's high-end graphics cards are not the slim components they once were. With their fat heatsinks and fans, GPUs like Nvidia's GeForce RTX 4090 turn the flat into a townhouse condo. However, the YouTube channel Optimum Tech (OT) used a water-cooling mod to turn the Nvidia behemoth into a slim folio-sized card.

Optimum Tech said this is probably not an ideal solution for most PC builds, but water cooling is a bit niche anyway. However, it said that the smaller footprint could come in handy in enterprise server applications. That said, OT plans to install the card into its main rig to see how it performs compared to its current setup. For now, it just ran it from an open bench.

The mod used is Alphacool's ES water block. It is only compatible with a few RTX 4090 models. Optimum Tech used an iChill Inno3D card in this case. The conversion to a water-cooled GPU resulted in a card that could easily fit in an ITX case --- just 210mm long and slim enough for one case slot.

While testing it on an open bench, Optimum Tech found that performance was on par with other alternatives like MSI's Suprim Liquid X. It ran God of War and Control at frame rates above 100fps with GPU temperatures only rising to about 53 degrees Celsius. However, performance within a case can significantly vary. Optimum Tech recommends running it in a dual-radiator setup.

Again, Alphacool designed this water block to reduce graphic card size and fit more into a rack. However, nothing is stopping adventurous builders from incorporating the mod into current or upcoming rigs, as OT intends to do soon. The block sells for $166.36US from Australian retailer Aquatuning.